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cost of linear actuators

Discussion in 'Electronic Design' started by Eric Anderson, Nov 3, 2007.

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  1. I have an application where I have to move a 3 lb object in a 3 ft
    cubic space. I am not looking at high performance or high accuracy.
    It can take as much as 30 seconds to traverse the 3 ft distance and
    the accuracy could be no better than 0.020 or 0.050 inch (possibly the
    spec could be even looser).

    Linear actuators would appear to be the best solution, but I am
    finding that they are hundreds or even thousands of dollars. The
    product I want to build will have to cost no more than $2,000 for a 3
    axis device with controller, overhead and profit.

    What is it in a linear actuator that costs so much that you could not
    build a low cost version using a threaded rod, servo or stepper motor
    and an extruded frame for a lot less?

    Does anyone know of a linear actuator that can provide the kind of
    performance I am looking for for a couple hundred dollars?
  2. Jim Stewart

    Jim Stewart Guest

    You used to be able to buy 1 - 2 foot
    actuators cheap. They were used to
    position the big K band satellite dishes.
    Don't know if they are still available.
  3. Well, each day the "ego" and "I wanna be a millionaire by tommarrow" taxes
    go up. They actually have a college course that preaches to its students
    that they have a god given right to make as much money as they can and do as
    little work as possible.... I think its called ethics and morality or
    something like that. Its a big hit with the medical and law students. The
    engineering students are doing well in it.
  4. Jim Stewart

    Jim Stewart Guest

    That's useful...
  5. Don Bowey

    Don Bowey Guest

    I can't see exactly who it is you are attempting to slam with that drivel.
    What do you mean by "Its a big hit with the medical and law students. The
    engineering students are doing well in it."
  6. MK

    MK Guest

    Try who have lots of cheap(ish) actuators. They are used in
    furniture and aids for the disabled.

    If you are in the US they may have an agent or there will be US suppliers
    serving the same market.

    Michael Kellett
  7. PeterD

    PeterD Guest

    Stepper motor/belt drive? Tear in to a couple of old ink jet printers
    and see what they do, then multiply the belt size to a length that
    meets your needs. You should get the accuracy you need. As to the
    weight of the object, you will either need gearing or a large stepper
    motor, 3 lb is heavier than a print head...
  8. Tim Wescott

    Tim Wescott Guest

    Linear actuators that are sold into industry are designed to work in
    anything, bear overload, be easy to engineer around, last forever, and
    look good while they're doing it. So of course they're expensive.

    If you're going to be building in volume (even modest volume like
    100/year) and it's not an aerospace application or a work-anywhere
    industrial application then you may do better building your own, or
    looking in some of the places others have suggested.

    You may also want to look in the Granger's catalog under "jackscrews".
    With the right controller and position sensor, these may do what you want.
    You may also want to consider hydraulics or pneumatics to get the job done
    -- once again you'll have a challenge to find economical parts, but you'll
    reduce your motor requirements to one and your actuators will get smaller.

    Sounds like a fun project.

    Tim Wescott
    Control systems and communications consulting

    Need to learn how to apply control theory in your embedded system?
    "Applied Control Theory for Embedded Systems" by Tim Wescott
  9. Jamie

    Jamie Guest

    Steel cable loop drive.?

    fine Acme threaded traverse screw ?
  10. default

    default Guest

    You certainly can build a "lead screw and follower" actuator for a lot
    less than thousands - motor and couple of limit switches?

    Or motor with a disk and offset pin like a crankshaft to translate
    rotary into linear motion.

    Don't overlook air cylinders. 3 feet is expensive for a cylinder but
    if you can get by with a shorter cylinder with mechanical advantage
    they have lots of advantages.

    My OM put a satellite dish actuators on his drive way gates. Lot of
    hassle running 120 out there and weather proof and in code. All kinds
    of problems when something kept the gate from closing or opening
    completely (like snow, ice, leaves, debris) and there was the overkill
    necessary to make it work. A few air cylinders fixed it with no
    hassle - 1/4" OD tubing, the actuators can stay stalled all day long
    with nothing to burn out, speed is easy to adjust with a valve,
    pressure is also easy to adjust. The only hard part was finding a
    pressure switch that would work with the 30 PSI diaphragm pump we had
    - the rest of it was hardware store parts.
  11. I understand that I could design the components myself. Ultimately I
    expect to be building low production quantities of these and was
    hoping that a linear actuator/controller combination might exist in
    the marketplace so I don't have to redesign the wheel. It will be
    required to work in an office environment. I have designed high-speed
    line printers and automotive sensors in my career, so I could build
    one of these. However, I don't want to find (as I have in the past)
    that a simple, low cost solution exists that I could use out-of-the-
    box and that is already being built in production quantities.
    Ideally, I would like to have 3 linear actuators, 2 of which would be
    on an X-Y base and the 3rd that would travel vertically from this X-Y
    base (call this the Z axis). I would need to control the three with a
    controller that would be programmed from a computer program I would
    write for the specific application I have in mind. (I can't divulge
    the purpose of this device at this time in case there are patent
    issues). I need to be able to represent the position by an icon or
    representation of the position using a diagram on the computer
    screen. I would have be able to return to previous position (by
    storing the X-Y-Z coordinates).
  12. And the problem with a satellite dish leg is...?

    Many thanks,

    Don Lancaster voice phone: (928)428-4073
    Synergetics 3860 West First Street Box 809 Thatcher, AZ 85552
    rss: email:

    Please visit my GURU's LAIR web site at
  13. default

    default Guest

    Many years ago there was a demonstration robot that could do that,
    although probably couldn't swing three pounds around in its gripper.

    It came with a keyboard and you programmed it by laboriously slewing
    to the coordinate you wanted one axis at a time, storing that position
    then on to the next one. When you played it back the robot would move
    in all axis at the same time to get to the coordinate that you put in
    memory (one axis at a time). It could also pause for a predetermined
    time. It and had an RS232 connector. Forget what it was called. It
    was something like $300+ back in the age of DOS.

    I only came across it at work and had it do things like dial my phone
    and throw switches. No idea why the company bought it. The precision
    was excellent - geared stepper motors moving push pull braided steel

    I'm not aware of any ready made, inexpensive, linear positioners that
    meet your specs. Maybe some of the robotic or radio control groups?

    Lots of hobby interest in modifying the mechanics of scanners to
    become X - Y tables - but not 3 foot swings.
  14. default

    default Guest

    Do they have feedback or just go to one of two positions and stop?

    I bought a surplus one. It is incredibly strong. Has limit switches,
    a 24 VDC motor - but no position feedback. Total range of motion is
    <20 inches (he mentioned 36" in his original post)

    Mine raises and lowers my bed - homebrew " The Amazing! Craftmatic
    Adjustable Bed!"
  15. You just pointed out an error I made in my original post. I meant to
    say the cube was one (1) cubic foot (possibly slightly over that).
    That would be just over 1 foot in each of the X, Y and Z directions.
    Unfortunately I led everyone to think 3 times what I really needed.

  16. default

    default Guest

    I guess I see the problem. A quick search of CNC / XYZ positioners
    yields tons of web sites - all seeming to have incredible load
    capacities and impressive positioning accuracies - which has to cost.
    And since many of them don't give representative prices leads me to
    believe they are expensive.

    Maybe one technique would be to determine your needs and anticipated
    quantities and start phoning or emailing around.

    Try posting to a forum - these folks are building that stuff Lot of pictures showing how others have done
    it (but you have to register to get past the thumbnails)

    Another search term might be Cartesian robot or gantry robot for a DIY
    site. Place I worked at had a laboratory (Cartesian) robot would do
    exactly what you want (for about $5K+ but that did include the
    computer and software and table)

    3 pounds is probably more than any normal scanner positioner can
    support directly. They do put Dremel tools on scanners for table top
    CNC machines but a Dremel probably only weighs a pound or so.

    Satellite dish positioners are probably overkill even if you find one
    with feedback. Mine can easily lift 150 pounds takes ~30 seconds to
    fully extend/retract - very heavy construction.
  17. C band:

    Service to my country? Been there, Done that, and I've got my DD214 to
    prove it.
    Member of DAV #85.

    Michael A. Terrell
    Central Florida
  18. Think about it: Who would buy cheap, consumer-grade actuators for
    mass-produced items when they can be made even cheaper and better suited to
    the task by integrating them into the product itself, like scanners and

    There simply is no market, so all you can get is heavy-duty,
    industrial-grade stuff.

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